U.S. patent application number 09/860116 was filed with the patent office on 2002-01-24 for lead free liner composition for shaped charges.
Invention is credited to Harvey, William, Henderson, Steve, Reese, James W., Slagle, Terry.
Application Number | 20020007754 09/860116 |
Document ID | / |
Family ID | 26901035 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020007754 |
Kind Code |
A1 |
Reese, James W. ; et
al. |
January 24, 2002 |
Lead free liner composition for shaped charges
Abstract
A liner for a shaped charge formed from a mixture of powdered
heavy metal and a powdered metal binder. The liner is formed by
compression of the mixture into a liner body shape. In the
preferred embodiment of the invention, the mixture comprises a
range of 90 to 97 percent by weight of powdered heavy metal, and 10
to 3 percent by weight of the powdered metal binder. In a specific
embodiment of the invention, a lubricant is intermixed with the
powdered metal binder to aid in the formation of the shaped charge
liner. The preferred powdered heavy metal is tungsten, and the
preferred powdered metal binder is copper. The powdered metal
binder can be comprised of other malleable ductile metals such as
bismuth, zinc, tin, uranium, silver, gold, antimony, cobalt, zinc
alloys, tin alloys, nickel, or palladium.
Inventors: |
Reese, James W.; (Spring,
TX) ; Henderson, Steve; (Katy, TX) ; Harvey,
William; (Indian Head, MD) ; Slagle, Terry;
(Cypress, TX) |
Correspondence
Address: |
DARRYL M. SPRINGS
BAKER ATLAS DIVISION OF BAKER HUGHES INCORPORATED
P.O. BOX 1407
HOUSTON
TX
77251
US
|
Family ID: |
26901035 |
Appl. No.: |
09/860116 |
Filed: |
May 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60206098 |
May 20, 2000 |
|
|
|
Current U.S.
Class: |
102/476 |
Current CPC
Class: |
F42B 1/032 20130101;
B22F 1/0003 20130101; B22F 2003/023 20130101; F42B 1/028 20130101;
C22C 1/045 20130101 |
Class at
Publication: |
102/476 |
International
Class: |
F42B 010/00 |
Claims
What is claimed is:
1. A liner for a shaped charge comprising: a mixture of powdered
heavy metal and powdered metal binder wherein said powdered heavy
metal comprises from 90 percent by weight of said mixture to 97
percent by weight of said mixture, and wherein said powdered metal
binder comprises from 10 percent by weight of said mixture to 3
percent by weight of said mixture, said mixture compressively
formed into a liner body shape.
2. The liner for a shaped charge of claim 1 further comprising a
lubricant intermixed with said tungsten and said powdered metal
binder.
3. The liner for a shaped charge of claim 2, wherein said lubricant
comprises powdered graphite.
4. The liner for a shaped charge of claim 2, wherein said lubricant
comprises oil.
5. The liner for a shaped charge of claim 1 wherein said powdered
metal binder is copper.
6. The liner for a shaped charge of claim 1 wherein said powdered
heavy metal is tungsten.
7. The liner for a shaped charge of claim 1 wherein said powdered
metal binder is selected from the group consisting of bismuth,
zinc, tin, uranium, silver, gold, antimony, cobalt, zinc alloys,
tin alloys, nickel, and palladium.
8. The liner for a shaped charge of claim 1, wherein said liner
body shape is selected from the group consisting of conical,
bi-conical, tulip, hemispherical, circumferential, linear, and
trumpet.
9. A shaped charge comprising: a housing; a quantity of explosive
inserted into said housing; and a liner inserted into said housing
so that said quantity of explosive is positioned between said liner
and said housing, said liner formed from a mixture of powdered
tungsten and powdered metal binder, wherein said powdered heavy
metal comprises from 90 percent by weight of said mixture to 97
percent by weight of said mixture, and wherein said powdered metal
binder comprises from 10 percent by weight of said mixture to 3
percent by weight of said mixture, said mixture compressively
formed into a liner body shape.
10. The liner for a shaped charge of claim 9 further comprising a
lubricant intermixed with said tungsten and said powdered metal
binder.
11. The liner for a shaped charge of claim 10, wherein said
lubricant comprises powdered graphite.
12. The liner for a shaped charge of claim 10, wherein said
lubricant comprises oil.
13. The liner for a shaped charge of claim 9 wherein said powdered
heavy metal is tungsten.
14. The liner for a shaped charge of claim 9 wherein said powdered
metal binder is copper.
15. The shaped charge of claim 9 further comprising a booster
explosive disposed in said housing and in contact with said
quantity of explosive, said booster explosive for transferring a
detonating signal from a detonating cord in contact with the
exterior of said housing to said high explosive.
16. The liner for a shaped charge of claim 9, wherein said liner
body shape is selected from the group consisting of conical,
bi-conical, tulip, hemispherical, circumferential, linear, and
trumpet.
17. The shaped charge of claim 9 wherein said quantity of explosive
comprises RDX.
18. The shaped charge of claim 9 wherein said quantity of explosive
comprises HMX.
19. The shaped charge of claim 9 wherein said quantity of explosive
comprises HNS.
20. The shaped charge of claim 9 wherein said quantity of explosive
comprises HNIW.
21. The shaped charge of claim 9 wherein said quantity of explosive
comprises TNAZ.
22. The shaped charge of claim 9 wherein said quantity of explosive
comprises PYX.
Description
RELATED APPLICATIONS
[0001] This application claims priority from co-pending U.S.
Provisional Application No. 60/206098, filed May 19, 2000, the full
disclosure of which is hereby incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates generally to the field of explosive
shaped charges. More specifically, the present invention relates to
a composition of matter for use as a liner in a shaped charge,
particularly a shaped charge used for oil well perforating.
[0004] 2. Description of Related Art
[0005] Shaped charges are used for the purpose, among others, of
making hydraulic communication passages, called perforations, in
wellbores drilled through earth formations so that predetermined
zones of the earth formations can be hydraulically connected to the
wellbore. Perforations are needed because wellbores are typically
completed by coaxially inserting a pipe or casing into the
wellbore, and the casing is retained in the wellbore by pumping
cement into the annular space between the wellbore and the casing.
The cemented casing is provided in the wellbore for the specific
purpose of hydraulically isolating from each other the various
earth formations penetrated by the wellbore.
[0006] Shaped charges known in the art for perforating wellbores
are used in conjunction with a perforation gun and the shaped
charges typically include a housing, a liner, and a quantity of
high explosive inserted between the liner and the housing where the
high explosive is usually HMX, RDX PYX, or HNS. When the high
explosive is detonated, the force of the detonation collapses the
liner and ejects it from one end of the charge at very high
velocity in a pattern called a "jet". The jet penetrates the
casing, the cement and a quantity of the formation. The quantity of
the formation which may be penetrated by the jet can be estimated
for a particular design shaped charge by test detonation of a
similar shaped charge under standardized conditions. The test
includes using a long cement "target" through which the jet
partially penetrates. The depth of jet penetration through the
specification target for any particular type of shaped charge
relates to the depth of jet penetration of the particular
perforation gun system through an earth formation.
[0007] In order to provide perforations which have efficient
hydraulic communication with the formation, it is known in the art
to design shaped charges in various ways to provide a jet which can
penetrate a large quantity of formation, the quantity usually
referred to as the "penetration depth" of the perforation. One
method known in the art for increasing the penetration depth is to
increase the quantity of explosive provided within the housing. A
drawback to increasing the quantity of explosive is that some of
the energy of the detonation is expended in directions other than
the direction in which the jet is expelled from the housing. As the
quantity of explosive is increased, therefore, it is possible to
increase the amount of detonation-caused damage to the wellbore and
to equipment used to transport the shaped charge to the depth
within the wellbore at which the perforation is to be made.
[0008] The sound speed of a shaped charge liner is the theoretical
maximum speed that the liner can travel and still form a coherent
"jet". If the liner is collapsed at a speed that exceeds the sound
speed of the liner material the resulting jet will not be coherent.
The sound speed of a liner material is calculated by the following
equation, sound speed=(bulk modulus /density).sup.1/2 (Equation
1.1). A coherent jet is a jet that consists of a continuous stream
of small particles. A non-coherent jet contains large particles or
is a jet comprised of multiples streams of particles. Increasing
the collapse speed of the liner will in turn increase jet tip
speeds. Increased jet tip speeds are desired since an increase in
jet tip speed increases the kinetic energy of the jet which in turn
provides increased well bore penetration. Therefore, a liner made
of a material having a higher sound speed is preferred because this
provides for increased collapse speeds while maintaining jet
coherency.
[0009] Accordingly, it is important to supply a detonation charge
to the shaped charge liner that does not cause the shaped charge
liner to exceed its sound speed. On the other hand, to maximize
penetration depth, it is desired to operate shaped charge liners at
close to their sound speed and to utilize shaped charge liners
having maximum sound speeds. Furthermore, it is important to
produce a jet stream that is coherent because penetration depth of
coherent jet streams is greater than the penetration depth of
non-coherent jet streams.
[0010] As per Equation 1.1 adjusting the physical properties of the
shaped charge liner materials can affect the sound speed of the
resulting jet. Furthermore, the physical properties of the shaped
charge liner material can be adjusted to increase the sound speed
of the shaped charge liner, which in turn increases the maximum
allowable speed to form a coherent jet. Knowing the sound speed of
a shaped charge liner is important since theoretically a shaped
charge liner will not form a coherent jet if the jet speed well
exceeds the sound speed of the shaped charge liner.
[0011] It is also known in the art to design the shape of the liner
in various ways so as to maximize the penetration depth of the
shaped charge for any particular quantity of explosive. Even if the
shape and sound speed of the shaped charge liner is optimized, the
amount of energy which can be transferred to the liner for making
the perforation is necessarily limited by the quantity of
explosive.
[0012] Shaped charge performance is dependent on other properties
of the liner material. Density and ductility are properties that
affect the shaped charge performance. Optimal performance of a
shaped charge liner occurs when the jet formed by the shaped charge
liner is long, coherent and highly dense. The density of the jet
can be controlled by utilizing a high density liner material. Jet
length is determined by jet tip velocity and the jet velocity
gradient. The jet velocity gradient is the rate at which the
velocity of the jet changes along the length of the jet whereas the
jet tip velocity is the velocity of the jet tip. The jet tip
velocity and jet velocity gradient are controlled by liner material
and geometry. The higher the jet tip velocity and the jet velocity
gradient the longer the jet. In solid liners, a ductile material is
desired since the solid liner can stretch into a longer jet before
the velocity gradient causes the liner to begin fragmenting. In
porous liners, it is desirable to have the liner form a long,
dense, continuous stream of small particles. To produce a coherent
jet, either from a solid liner or a porous liner; the liner
material must be such that the liner does not splinter into large
fragments after detonation.
[0013] The solid shaped charge liners are formed by cold working a
metal into the desired shape, others are formed by adding a coating
onto the cold formed liner to produce a composite liner.
Information relevant to cold worked liners is addressed in Winter
et al., U.S. Pat. No. 4,766,813, Ayer U.S. Pat. No. 5,279,228, and
Skolnick et al., U.S. Pat. No. 4,498,367. However, solid liners
suffer from the disadvantage of allowing "carrots" to form and
become lodged in the resulting perforation--which reduces the
hydrocarbon flow from the producing zone into the wellbore. Carrots
are sections of the shaped charge liner that form into solid slugs
after the liner has been detonated and do not become part of the
shaped charge jet. Instead the carrots, which can take on an oval
shape, travel at a velocity that is lower than the shaped charge
jet velocity and thus trail the shaped charge jet.
[0014] Porous liners are formed by compressing powdered metal into
the desired liner shape. Traditional liner shapes are conical,
linear, and hemispherical. Typically, the liners that have been
formed by compressing powdered metals have utilized a composite of
two or more different metals, where at least one of the powdered
metals is a heavy or higher density metal, and at least one of the
powdered metals acts as a binder or matrix to bind the heavy or
higher density metal. Examples of heavy or higher density metals
used in the past to form liners for shaped charges have included
tungsten, hafnium, copper, or bismuth. Typically the binders or
matrix metals used comprise powdered lead, however powdered bismuth
has been used as a binder or matrix metal. While lead and bismuth
are more typically used as the binder or matrix material for the
powdered metal binder, other metals having high ductility and
malleability can be used for the binder or matrix metal. Other
metals which have high ductility and malleability and are suitable
for use as a binder or matrix metal comprise zinc, tin, uranium,
silver, gold, antimony, cobalt, copper, zinc alloys, tin alloys,
nickel, and palladium. Information relevant to shaped charge liners
formed with powdered metals is addressed in Werner et al., U.S.
Pat. No. 5,221,808, Werner et al., U.S. Pat. No. 5,413,048, Leidel,
U.S. Pat. No. 5,814,758, Held et al. U.S. Pat. No. 4,613,370, Reese
et al., U.S. Pat. No. 5,656,791, and Reese et al., U.S. Pat. No.
5,567,906.
[0015] However, each one of the aforementioned references related
to powdered metal liners suffer from the disadvantages of liner
creep, and/or a high percentage of binder material in the material
mix. Liner creep involves the shaped charge liner slightly
expanding after the shaped charge has been assembled and stored.
Slight expansion of the shaped charge liner reduces shaped charge
effectiveness and repeatability.
[0016] The binder or matrix material typically has a lower density
than the heavy metal component. Accordingly the overall density of
the shaped charge liner is reduced when a significant percentage of
the shaped charge liner is comprised of the binder or matrix
material. Reducing the overall density of the shaped charge liner
reduces the penetration depth produced by the particular shaped
charge.
[0017] Therefore, it is desired to produce a shaped charge liner
that is not subject to creep, has an improved overall density, and
a high sound speed.
BRIEF SUMMARY OF THE INVENTION
[0018] The present invention solves a number of the problems
inherent in the prior art by providing a liner for a shaped charge
comprising a mixture of powdered tungsten and powdered metal binder
wherein the tungsten powder comprises from 90 percent by weight of
the mixture to 97 percent by weight of the mixture. The powdered
metal binder comprises from 10 percent by weight of the mixture to
3 percent by weight of the mixture. The liner for a shaped charge
is formed by compressing the mixture into a liner body shape, where
the shape can be chosen from the group consisting of conical,
bi-conical, tulip, circumferential, hemispherical, linear or
trumpet. The liner for a shaped charge further comprises a
lubricant such as powdered graphite or oil intermixed with the
tungsten and the powdered metal binder. While the preferred
powdered metal binder is copper, the powdered metal binder can also
consist of bismuth, zinc, tin, uranium, silver, gold, antimony,
cobalt, zinc alloys, tin alloys, nickel, or palladium. Other and
further features and advantages will be apparent from the following
description of presently preferred embodiments of the invention
given for the purpose of disclosure.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING.
[0019] FIG. 1 depicts a cross-sectional view of a shaped charge
with a liner according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] In accordance with the present invention, a shaped charge 10
according to the invention is shown in FIG. 1. The shaped charge 10
typically includes a generally cylindrically shaped housing 1,
which can be formed from steel, ceramic or other material known in
the art. A quantity of high explosive powder, shown generally at 2,
is inserted into the interior of the housing 1. The high explosive
2 can be of a composition known in the art. High explosives known
in the art for use in shaped charges include compositions sold
under trade designations HMX, HNS, RDX, HNIW, PYX and TNAZ. A
recess 4 formed at the bottom of the housing 1 can contain a
booster explosive (not shown) such as pure RDX. The booster
explosive, as is understood by those skilled in the art, provides
efficient transfer to the high explosive 2 of a detonating signal
provided by a detonating cord (not shown) which is typically placed
in contact with the exterior of the recess 4. The recess 4 can be
externally covered with a seal, shown generally at 3.
[0021] A liner, shown at 5, is typically inserted on to the high
explosive 2 far enough into the housing 1 so that the high
explosive 2 substantially fills the volume between the housing 1
and the liner 5. The liner 5 of FIG. 1 is typically made from
powdered metal which is pressed under very high pressure into a
generally conically shaped rigid body. The conical body is
typically open at the base and is hollow. Compressing the powdered
metal under sufficient pressure can cause the powder to behave
substantially as a solid mass. The process of compressively forming
the liner from powdered metal is understood by those skilled in the
art.
[0022] As will be appreciated by those skilled in the art, the
liner 5 of the present invention is not limited to conical or
frusto-conical shapes, but can be formed into numerous shapes.
Additional liner shapes can include bi-conical, tulip,
hemispherical, circumferential, linear, and trumpet.
[0023] As is further understood by those skilled in the art, when
the explosive 2 is detonated, either directly by signal transfer
from the detonating cord (not shown) or transfer through the
booster explosive (not shown), the force of the detonation
collapses the liner 5 and causes the liner 5 to be formed into a
jet, once formed the jet is ejected from the housing 1 at very high
velocity.
[0024] A novel aspect of the present invention is the composition
of the powdered metal from which the liner 5 can be formed. The
powdered metal mixture of the liner 5 of the present invention
preferably consists of 95 percent by weight of a powdered heavy
metal and 5 percent by weight of a powdered metal binder. The
preferred powdered heavy metal is tungsten, however the powdered
heavy metal can be any metal having acceptable acoustic wave
conducting ability, such as depleted uranium, hafnium, tantalum,
copper, or bismuth.
[0025] Optionally, lubricants such as graphite powder or oil can be
added to the powdered metal mixture. The graphite powder can be
added in an amount up to 1.0 percent by weight of the powdered
metal mixture. The addition of the lubricant will weight for weight
reduce the amount of powdered metal binder of the mixture. The
lubricant aids the formation of the shaped charge liner during the
forming process, as is understood by those skilled in the art. As
will be further explained, the penetration depth of the shaped
charge 10 is improved by using an increased percentage of powdered
tungsten in the liner 5 material, compared with the depth of
penetration achieved by shaped charges having liners of
compositions known in the art which use lesser mass percentages of
powdered tungsten.
[0026] The powdered metal binder can be comprised of the highly
ductile or malleable metals selected from the group consisting of
bismuth, zinc, tin, uranium, silver, gold, antimony, cobalt,
copper, zinc alloys, tin alloys, nickel, copper, and palladium.
However, the preferred powdered metal binder is powdered copper.
Using copper as the powdered metal binder instead of the above
noted powdered metal binders, especially with regard to lead,
results in a shaped charge liner having a higher sound speed. As
noted above, higher sound speeds are desired since higher jet speed
results in an increased penetration depth.
[0027] Additionally, copper has a lower density than most of the
other traditional binder metals, especially lead. A lower density
powdered metal binder results in an increase in volume of the
powdered metal binder. More powdered metal binder volume results in
additional material that can act as a binder and thus better bind
the heavy metal. A lower density powdered metal binder thus allows
for a higher percentage of the heavy metal portion of the shaped
charge liner, which in turn contributes to an increased overall
sound speed of the shaped charge liner.
[0028] The specified amount of powdered metal binder in the liner
mixture in the preferred composition of 5 percent by weight is not
to be construed as an absolute limitation of the invention. A range
of compositions of powdered metal mixture, including powdered
tungsten up to 97 percent by weight and powdered metal binder of 3
percent by weight, down to powdered tungsten of 90 percent by
weight and powdered metal binder to 10 percent by weight has been
tested. It has been determined through this testing that mixture
compositions within the specified range still provide effective
shaped charge performance.
[0029] The liner 5 can be retained in the housing 1 by application
of adhesive, shown at 6. The adhesive 6 enables the shaped charge
10 to withstand the shock and vibration typically encountered
during handling and transportation without movement of the liner 5
or the explosive 2 within the housing 1. It is to be understood
that the adhesive 6 is only used for retaining the liner 5 in
position within the housing 1 and is not to be construed as a
limitation on the invention.
[0030] The present invention described herein, therefore, is well
adapted to carry out the objects and attain the ends and advantages
mentioned, as well as others inherent therein. While a presently
preferred embodiment of the invention has been given for purposes
of disclosure, numerous changes in the details of procedures for
accomplishing the desired results. These and other similar
modifications will readily suggest themselves to those skilled in
the art, and are intended to be encompassed within the spirit of
the present invention disclosed herein and the scope of the
appended claims.
* * * * *